**10 Downing Street** serves as the official residence and principal office of the United Kingdom's Prime Minister, functioning as the nerve center of British government operations.[1][3][4] Housing around 100 rooms in a Grade I listed building over 300 years old, it supports the Prime Minister in crafting policy, coordinating across government departments, resolving disputes, tracking priorities, and managing communications with Parliament, the public, media, and international audiences.[1][3] Its history traces back to the late 17th century on the site of a medieval brewery near the ruins of Whitehall Palace. Originally three modest houses, Number 10 was gifted by King George II to Sir Robert Walpole in 1732, who became Britain's first de facto Prime Minister in 1735, merging the roles of First Lord of the Treasury and Prime Minister.[2][4][6] Early residents like George Monck modernized Treasury accounting, while expansions connected it to Numbers 11 (Chancellor's residence) and 12 (press and strategy units).[2][4] Key achievements include hosting iconic leaders—Walpole, Gladstone, Disraeli, Churchill, Thatcher—and pivotal moments, from wartime cabinets to global summits outside its famous black door.[4][6] The site's evolution reflects Britain's constitutional shifts, like separating Prime Minister and Chancellor roles in the 19th century.[4] Today, No. 10 operates like a "small Government Department" with about 250 staff, including civil servants, special advisers, and specialized units (policy, data science, delivery, legislative).[1][3] It works closely with the Cabinet Office, though its growth has sparked debates on complexity, as seen in the 2021 "partygate" inquiry.[1] Ongoing reforms, like the "Plan for Change," aim to sharpen its strategic edge.[8] Notably unassuming externally—like a TARDIS inside—Downing Street symbolizes enduring power, blending histor